In tire curing, where post inflation is employed, one of the most common defects is known as a "no PCI" defect. This means that for some reason the tire was not properly subjected to the required post cure inflation. When post cure inflation is employed, it is usually accomplished by a separate machine positioned at the rear of the tire shaping and curing press. In order to be positioned properly in the post cure inflator, the tire must be restrained or recaught after discharge from the press and properly centered for engagement with the bead engaging rims when the post cure inflator closes. Many post cure inflators use inclined conveyors which are a continuation of the discharge conveyor of the press. Tires can achieve a substantial momentum which is oftentimes accentuated by the unloading mechanism of the press. Usually, restraint and centering devices engage the outside or tread of the tire and are complex and costly, requiring adjustment for different sizes and shapes of tires.
A common complaint about post cure inflators is that tire restraint or centering devices fail to perform properly and tires have been known to pass completely through a post cure inflator. Obviously, if the tire is not properly centered, a defective tire may result.
Attempts have been made to provide greater reliability for post cure inflators. For example, power driven horizontally disposed conveyor belts have been employed to reduce the momentum of the tire as it moves into the post cure inflator. While somewhat effective, such belt drives still require outside centering and add to the cost of equipment. Moreover, with outside centering, the post inflation rings generally require complex relatively large interfitting pilot surfaces such as shown in Brundage U.S. Pat. No. 3,170,187 dated Feb. 23, 1965. While such patent illustrates an attempt to achieve a ring which will seat and inflate tires of differing bead diameters, obviously, without proper centering for all of the various steps of the ring, such ring cannot achieve the purpose intended. The pilot surface will be effective to center the tire only with regard to the smallest bead seat. Accordingly, applicants are not aware of any automatic post cure inflator wherein a single bead ring has been employed successfully to inflate tires of differing bead diameters.
One attempt to solve some of the above outlined problems is disclosed in the copending application of Gerald J. Yuhas et al, Ser. No. 797,938 filed May 18, 1977 now U.S. Pat. No. 4,092,090, dated May 30, 1978 entitled "Tire Curing System", and assigned to the assignee of the present application. In such copending application there is illustrated a press-post inflator combination wherein the press places the tire directly onto or in the post cure inflator. While the tire curing system of the aforementioned patent does confront some of the problems met by the invention of this application, it represents a relatively costly solution requiring a substantial capital investment. It cannot solve the problem in press lines already in existence.